1999 C70 the engine is hard to start and stalls when you stop

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2001 Volvo C70 Problems - RepairPal

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Ignition or fuel problem probably . When you turn the key to start does the engine spin ? Crank no start or nothing happens NO CRANK - NO START ?
If the engine spins an does not start an run you need to test to see what's missing Spark or fuel . Pull a spark plug wire off a spark plug an stick a screw driver in the end an hold it near ground (metal) and have someone try to start the vehicle ! Is there spark ? Spray starting fluid into the engine , does it start then ?
Videos on youtube showing how to do these tests

sounds like your torque is locking up,have it checked

that is called engine stalling
all car when the engine stalled, the braking assest (helper) goes
dead. (loss of engine vacuum is cause, and is normal in all stalls)
we had to learn this in driving school in 1960, due to stalls then
are COMMON as nails, but the brakes still work. and ONLY takes more pressure with your foot ,
top cause of all stalls (and in 1960) is not getting a tuneup
ALL cars do this if you IGNORED basic SERVICE.
The ENGINE light came on
that means "get the car serviced," if you have tools it means
to a real shop SCAN it.
way ask blind web bunnies, this, we can diagnose your car,
or force you go get it serviced,
stalls have over 50 causes, a tuneup is top of list since 1884.
That old car in France sill runs and is serviced,proper.

try not to assume things, like pump or anything on car
can not be intermittent, (in fact assume it can and win)
get the car serviced
the operators guide, open it ? see the CHECK engine lamp page
see what it states........bingo

Vent valve has failed closed or cannister is clogged up. Have the evap system checked from the tank to the charcoal canister. If you need to drive to a mechanic, try driving with the gas cap loose.

FIrst have you tried giving the engine a tune up (ie replaced the spark plugs)

Also you need to check the condition of all the vacumn lines on the engine loss of vacumn can cause poor idling.

Check The Mass Air Flow Sensor.. Check engine Light Coming On?

I would start with the Fuel Pump Relay. Check the Fuel Pump, Fuel Filter and Belt Tension.

i had the same problem once before makeshure the gas lines arent coroded or kenked if that dont work try cleaning the fuel injectors.

need to to do a injector test